The detection of knocking in an internal combustion engine is described, for example, in DE 103 00 204 AI. Abnormal combustion processes, described as “knocking”, occurring in combustion chambers of internal combustion engines (in particular, for example, as a result of spontaneous unintended self-ignition of a combustible mixture) are detected by means of one or more knock sensors in accordance with the prior art. As knocking only makes itself known in one or more specific frequency ranges, bandpass filtering of the knock sensor signal is necessary. In the detection of knocking known from DE 103 00 20 204 A1, a filter which is not described in more detail with regard to structure and function is provided with bandpass characteristics for this purpose.
For reliable detection or distinction of knocking, whether combustion occurs with knocking or not, the quality of bandpass filtering during the processing of the knock sensor signal is of great importance.
U.S. Pat. No. 7,181,339 B2 discloses a device for real-time spectrum analysis of a knock signal in an internal combustion engine in which for signal processing an analog filter, a sigma-delta modulator designed for analog-digital conversion, and a CIC filter designed to decimate the sampling rate, are arranged in tandem. However, this only enables analysis of the knock signal but not use in an engine control device yet.
DE 100 04 166 A1 discloses a device for the detection of knocking in an internal combustion engine with at least one knock sensor assigned to a cylinder of the internal combustion engine, in which the actual detection of knocking takes place using purely digital components, the components typical of knocking being extracted from the edited and digitized output signals of the knock sensor or the knock sensors and for knock detection compared with definable thresholds which can be changed if necessary. Digital signal evaluation or the digital component is exemplary for three different embodiments. On the one hand, the digital component may comprise a filter, a rectifier and an integrator or it may comprise a means of performing a discrete Fourier transformation or a means of performing a rapid Fourier transformation.